N/C. Rext. (Optional) GND

Transcription

1 BC42U BC421U LINEA LED CONSTANT CUT EGULATO IN U-DFN22-6 Descriptin The BC42U and BC421U mnlithically integrate transistrs, dides and resistrs t functin as a Cnstant Current egulatr (CC) fr linear LED driving. The device regulates with a preset 1mA nminal that can be adjusted with an external resistr up t 35mA. It is designed fr driving LEDs in strings and will reduce current at increasing temperatures t self-prtect. Operating as a series linear CC fr LED string current cntrl, it can be used in multiple applicatins, as lng as the maximum supply vltage t the device is < 4. With the lw-side cntrl, the BC421U has an Enable () pin which can be pulse-width mdulated (PWM) up t 25kHz by a micrcntrller fr LED dimming. With n need fr additinal external cmpnents, this CC is fully integrated int a 2x2x.6mm package (U-DFN22-6) minimizing PCB area, ff-bard height, and cmpnent cunt. Applicatins Cnstant Current egulatin (CC) in: Edge Lighting Strips Emergency Lighting Signage, Advertising, Decrative and Architectural Lighting etail Lighting in Fridges, Freezer Cases and ending Machines Features LED Cnstant Current egulatr Using NPN Emitter-Fllwer with Emitter esistr t Current Limit I 1mA ±1% Cnstant Current (Preset) I up t 35mA Adjustable with an External esistr (BC421U) 4 Supply ltage P D up t 1.7W in U-DFN22-6 Package.6mm Height fr Lw-prfile Edge Lighting Lw-Side Cntrl Enabling PWM Input < 25kHz (BC421U) Negative Temperature Cefficient (NTC) educes I with Increasing Temperature Parallel Devices t Increase egulated Current Ttally Lead-Free & Fully HS Cmpliant (Ntes 1 & 2) Halgen and Antimny Free. Green Device (Nte 3) Autmtive-Cmpliant Parts are Available Under Separate Datasheet (BC42UFDQ/BC421UFDQ) Mechanical Data Case: U-DFN22-6 Case Material: Mlded Plastic. Green Mlding Cmpund. UL Flammability ating 94- Misture Sensitivity: Level 1 per J-STD-2 Terminals: Finish - NiPdAu, Slderable per MIL-STD-22, Methd 28 e4 Weight:.18 grams (Apprximate) U-DFN22-6 Bttm iew Internal Device Schematic ext (Optinal) GND N/C N/C Tp iew Pin-Out GND ext Pin Name ext GND N/C Pin Functin egulated Output Current Enable fr Biasing Transistr External esistr fr Adjusting Output Current Pwer Grund Nt cnnected internally Ordering Infrmatin (Nte 4) Part Number Cmpliance Marking eel Size (inches) Tape Width (mm) Quantity Per eel BC42UFD-7 Standard , BC421UFD-7 Standard , Ntes: 1. N purpsely added lead. Fully EU Directive 22/95/EC (HS), 211/65/EU (HS 2) & 215/863/EU (HS 3) cmpliant. 2. See fr mre infrmatin abut Dides Incrprated s definitins f Halgen- and Antimny-free, "Green" and Lead-free. 3. Halgen- and Antimny-free "Green prducts are defined as thse which cntain <9ppm brmine, <9ppm chlrine (<15ppm ttal Br + Cl) and <1ppm antimny cmpunds. 4. Fr packaging details, g t ur website at Dcument number: DS38588 ev f 13

2 Marking Infrmatin xxx xxx = Part Marking (See Ordering Infrmatin) Y = Year: ~9 W = Week: A~Z: 1~26 week; a~z; 27~52 week; z represents 52 and 53 week Abslute Maximum atings (ltage relative t A = +25 C, unless therwise specified.) Enable ltage Characteristic Symbl alue Unit BC42U BC421U 18 Output Current I 5 ma Output ltage 4 everse ltage Between all Terminals.5 4 Thermal Characteristics (@T A = +25 C, unless therwise specified.) Pwer Dissipatin Thermal esistance, Junctin t Ambient Characteristic Symbl alue Unit (Nte 5) P D 1.7 (Nte 6) 1.3 (Nte 5) θja (Nte 6) 1 Thermal esistance, Junctin t Lead (Nte 7) θjl 35 C/W ecmmended Operating Junctin Temperature ange T J -55 t +15 C Maximum Operating Junctin and Strage Temperature ange T J, T STG -65 t W C/W ESD atings (Nte 8) Electrstatic Discharge Human Bdy Mdel Characteristic Symbl alue Unit JEDEC Class Electrstatic Discharge Machine Mdel Ntes: BC42U 7 1B HBM BC421U 1 1C BC42U 3 B MM BC421U 4 C 5. Fr a device munted with the leads n 5mm x 5mm 1z cpper that is n a single-sided 1.6mm F-4 PCB; device is measured under still air cnditins while perating in steady-state. 6. Same as Nte 5, except munted n 25mm x 25mm 1z cpper. 7. θjl = Thermal resistance frm junctin t slder-pint (at the end f the leads). 8. efer t JEDEC specificatin JESD22-A114 and JESD22-A115. Dcument number: DS38588 ev f 13

3 Electrical Characteristics A = +25 C, unless therwise specified.) Characteristic Symbl Min Typ Max Unit Test Cnditin Cllectr-Emitter Breakdwn ltage B CEO 4 I C = 1mA Enable Current BC42U 1.2 = 24 I ma BC421U 1.2 = 3.3 DC Current Gain h FE I C = 5mA; CE = 1 Internal esistr INT Ω I INT = 1mA Bias esistr Output Current Output Current at = 5.1Ω BC42U 2 B kω BC421U 1.5 BC42U I ma = 1.4; = 24 BC421U ma = 1.4; = 3.3 BC42U I 15 ma > 2.; = 24 BC421U 15 ma > 2.; = 3.3 ltage Drp ( ) DOP I = 1mA Minimum Output ltage (MIN) 1.4 I > 18mA Output Current Change vs. Temperature Output Current Change vs. Supply ltage BC42U -.2 > 2.; = 24 ΔI /I %/ C BC421U -.2 > 2.; = 3.3 BC42U 1 > 2.; = 24 ΔI /I %/ BC421U 1 > 2.; = 3.3 Dcument number: DS38588 ev f 13

4 Thermal esistance ( C/W) Thermal esistance ( C/W) Maximum Pwer (W) Max Pwer Dissipatin (W) Typical Thermal Characteristics BC42/1U (@T A = +25 C, unless therwise specified.) mm * 1mm 5mm * 5mm 25mm * 25mm 15mm * 15mm Temperature ( C) Derating Curve 5 D=.5 D=.2 5mm * 5mm 25 Single Pulse 15mm * 15mm 1 D= 1mm * 1mm D=.1 1µ 1m 1m 1m k 1µ 1m 1m 1m k Pulse Width (s) Transient Thermal Impedance D=.5 D=.2 15mm * 15mm Single Pulse Pulse Width (s) Pulse Pwer Dissipatin 25 D= 1 Single Pulse 5mm * 5mm D=.1 T =25 C amb 1µ 1m 1m 1m k 1µ 1m 1m 1m k Pulse Width (s) Transient Thermal Impedance Thermal esistance ( C/W) th(ja) ( C/W) Cpper Area (mm 2 ) th(ja) S 1 z Cu Area Single Pulse T amb =25 C 15mm * 15mm 1mm * 1mm 5mm * 5mm 25mm * 25mm 25mm * 25mm Pulse Width (s) Pulse Pwer Dissipatin Dcument number: DS38588 ev f 13

5 Typical Electrical Characteristics BC421U A = +25 C, unless therwise specified.) =6.2 =3.3.2 =8.2 =5.4 =1.8 =15 = 3.4 =pen.15.1 =1.4 = () () vs I () vs I C C 85 C = C =3.3.3 =2.8 = () () vs I vs I C 85 C =2 =8.2-4 C.1 =3 =3.3 =6.2 = 6 =1 = pen =pen () () vs I vs I Dcument number: DS38588 ev f 13

6 I (ma) Typical Electrical Characteristics BC421U (Cnt.) A = +25 C, unless therwise specified.) 3.m m I =A 2.m =pen 85 C.1 25 C 1.5m 1.m 5.µμ C C C C =2 = 2 85 C = () 25 C -4 C () vs I vs I () vs I () vs I =2 =6.2 =pen Dcument number: DS38588 ev f 13

7 Typical Electrical Characteristics BC42U (Cnt.) A = +25 C, unless therwise specified.).2.16 = =24.2 =8.2 = 5.4 = =15.1 =1.4 = 3.4 =pen = C.8.6 () vs I.6 () ()vs I.4 25 C 85 C =24 85 C =24.3 =2 = () () vs I vs I =3 25 C =24 =2 =8 =2 =6 =1 ext 85 C =pen () () vs I vs I =pen Dcument number: DS38588 ev f 13

8 I (ma) Typical Electrical Characteristics BC42U (Cnt.) A = +25 C, unless therwise specified.) 3.m m I =A =pen 85 C 25 C 2.m.1 1.5m 1.m 5.µμ C -4 C () vs I 85 C 25 C.5 85 C =2 =pen () vs I 25 C 85 C =2 =2 =2 = () ( vs I. ) vs I Dcument number: DS38588 ev f 13

9 Applicatin Infrmatin The BC42/1 are designed fr driving lw current LEDs with typical LED currents f 1mA t 35mA. They prvide a cst-effective way fr driving lw current LEDs cmpared with mre cmplex switching regulatr slutins. Furthermre, they reduce the PCB bard area f the slutin as there is n need fr external cmpnents like inductrs, capacitrs and switching dides. (Optinal) (Optinal) Figure 1 shws a typical applicatin circuit diagram fr driving an LED r string f LEDs. The device cmes with an internal resistr ( INT) f typically 95Ω, which in the absence f an external resistr, sets an LED current f 1mA (typical) frm a = 3.3 and = 1.4 fr BC421; r = 24 and = 1.4 fr BC42. LED current can be increased t a desired value by chsing an apprpriate external resistr,. The vs I graphs shuld be used t select the apprpriate resistr. Chsing a lw tlerance will imprve the verall accuracy f the current sense frmed by the parallel cnnectin f INT and. Figure 1 Typical Applicatin Circuit fr Linear Mde Current Sink LED Driver Tw r mre BC42/1s can be cnnected in parallel t cnstruct higher current LED strings as shwn in Figure 2. Cnsideratin f the expected linear mde pwer dissipatin must be factred int the design, with respect t the BC42/1 s thermal resistance. The maximum vltage acrss the device can be calculated by taking the maximum supply vltage and subtracting the vltage acrss the LED string. = S LED P D = ( I LED) + ( I ) (Optinal) (Optinal) As the utput current f BC42/1 increases, it is necessary t prvide apprpriate thermal relief t the device. The pwer dissipatin supprted by the device is dependent upn the PCB bard material, the cpper area and the ambient temperature. The maximum dissipatin the device can handle is given by: P D = ( T J(MAX) - T A) / θja Figure 2 Applicatin Circuit fr Increasing LED Current efer t the thermal characteristic graphs n Page 4 fr selecting the apprpriate PCB cpper area. Dcument number: DS38588 ev f 13

10 Applicatin Infrmatin (Cnt.) PWM dimming can be achieved by driving the pin. Dimming is achieved by turning the LEDs ON and OFF fr a prtin f a single cycle. The PWM signal can be prvided by a micr-cntrller r analg circuitry; typical circuit is shwn in Figure 3. Figure 4 is a typical respnse f LED current vs. PWM duty cycle n the pin. PWM up t 25kHz with duty cycle f.5% (dimming range 2:1). This is abve the audi band minimizing audible pwer supply nise. (Optinal) Figure 3 Applicatin Circuits fr LED Driver with PWM Dimming Functinality using BC421U Figure 4 Typical LED Current espnse vs. PWM Duty Cycle fr 25kHz PWM Frequency (Dimming ange 2:1) Dcument number: DS38588 ev f 13

11 Applicatin Infrmatin (Cnt.) T remve the ptential f incrrect cnnectin f the pwer supply damaging the lamp s LEDs, many systems use sme frm f reverse plarity prtectin. One slutin fr reverse input plarity prtectin is t simply use a dide with a lw F in line with the driver/led cmbinatin. The lw F increases the available vltage t the LED stack and dissipates less pwer. A circuit example is presented in Figure 5 which prtects the light engine althugh it will nt functin until the prblem is diagnsed and crrected. An SDM1U45LP (.1A/45) is shwn, prviding exceptinally lw F fr its package size f 1mm x.6mm. Other reverse vltage ratings are available frm Dides Incrprated s website such as the SB2U1LP (.2A/1) r SB22LP (.2A/2). Figure 5 Applicatin Circuit fr LED Driver with everse Plarity Prtectin (Optinal) While autmtive applicatins cmmnly use this methd fr reverse battery prtectin, an alternative apprach shwn in Figure 6, prvides reverse plarity prtectin and crrects the reversed plarity, allwing the light engine t functin. The BAS4BW incrprates fur lw F Schttky dides in a single package, reducing the pwer dissipated and maximizes the vltage acrss the LED stack. Figure 7 shws an example cnfiguratin fr 35mA peratin using BC421U. In such higher current cnfiguratins adequate enable current is prvided by increasing the enable vltage. (Optinal) = 2.1 Figure 6 Applicatin Circuit fr LED Driver with Assured Operatin egardless Of Plarity Figure 7 Example fr 35mA Operatin using BC421U Dcument number: DS38588 ev f 13

12 Package Outline Dimensins Please see fr the latest versin. U-DFN22-6 A A1 D D2 D2/2 A3 Seating Plane U-DFN22-6 Dim Min Max Typ A A1.3 A b D D e E E L All Dimensins in mm E E2 E2/2 Pin #1 ID L e b Suggested Pad Layut Please see fr the latest versin. U-DFN22-6 Y X C G Y1 alue Dimensins (in mm) C.65 G.15 X.37 X Y.45 Y1.9 G X X1 Dcument number: DS38588 ev f 13

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